Conventionally, transistor, IC, LSI and the like semiconductor elements are manufactured as semiconductor devices by encapsulating them with plastic packages, e.g., using an epoxy resin compositions, from the viewpoint of protecting them from the external environment and enabling handling of the elements. Such an epoxy resin composition is obtained, for example, by mixing and kneading an epoxy resin, a phenol resin, a hardening accelerator, and other components such as a silane coupling agent and the like, using a mixing roller, a mixing pot, a kneader or the like. In order to improve dispersibility and wettability of respective components, a production method is employed in which certain parts of the components are pre-mixed in advance and then the remaining parts of the components are mixed with the resulting mixture.
As an example of such a production method, it has been proposed to prepare and use an epoxy resin hardener by mixing a novolak-type phenol resin hardener with tetraphenylphosphonium tetraphenylborate under heating (cf. Reference 1). The epoxy resin composition obtained by the above production method exerts an effect that the epoxy resin composition has good storage stability and the cured product has excellent moisture resistance.
On the other hand, a method has been proposed in which a part or entire portion of a phenol resin component is melt-mixed with an epoxy silane coupling agent and an amine hardening accelerator, and then this is melt-mixed with the remaining components (cf. Reference 2).
Reference 1: JP-B-56-45491
Reference 2: JP-B-7-35432